Foldable antenna operable in dual modes

ABSTRACT

A foldable antenna for mounting on a base member. A vertical mounting mast includes the base member at one end thereof and a cavity member at the other end. A plurality of rigid radiating elements depend from the cavity member and are threadably secured thereto. A plurality of rigid ground plane members extend from the base member in a plane perpendicular to the mounting mast and are threadably secured thereto. The radiating elements may be designed to transmit and receive circularly polarized waves. Further, the cavity may have a monopole radiating element threadably secured thereto in a plane parallel to the plane of the mounting mast and a second set of ground plane elements operatively associated with the monopole radiating element threadably secured to the cavity in a plane perpendicular to the mast. The radiating elements and the ground plane elements may be removed and transported in a carrying case member which encompasses the mounting mast between the cavity and the base member.

United States Patent [151 3,665,478 Dempsey 1 23, W72

[54] F OLDABLE ANTENNA ()PERABLE IN Primary Examiner-Eli Lieberman DUAL MODES AttorneyC. Cornell Remsen, Jr., Walter J. Baum, Paul W.

Hemminger, Charles L. Johnson, Jr. and Thomas E. Kristof- [72] Inventor: Richard C. Dempsey, 9718 Quartz Ave., fe n Chatsworth, Calif. 9131 l 22 Filed: Aug. 31, 1970 [57] ABSTRACT [21 AppL No; 68,132 A foldable antenna for mounting on a base member. A vertical mounting mast includes the base member at one end thereof and a cavity member at the other end. A plurality of rigid [52] U.S.CI ..343/725, 343/797, 343/846, radiating elements depend from the cavity member and are 343/880 threadably secured thereto. A plurality of rigid ground plane [51 II."- Cl. members extend from the base member in a plane p p i Fleld 0 Search ..343/724730, 773, to the mounting t and are threadably secured thereto 343/774 797 The radiating elements may be designed to transmit and receive circularly polarized waves. Further, the cavity may [56] References Cited have a monopole radiating element threadably secured UNITED STATES PATENTS thereto in a plane parallel to the plane of the mounting mast and a second set of ground plane elements operatively as- 2,298,449 10/ 1942 Bailey ..343/798 ociated with the monopole radiating element threadably 2.333.564 H1944 Afam secured to the cavity in a plane perpendicular to the mast. The 2,510,237 1950 Lane el 1 radiating elements and the ground plane elements may be 2,633,031 3/1954 Lapofl removed and transported in a carrying case member which en- 2,987,72l 6/1961 Edwards et aI. ..343/725 compasses the mounting mast between the cavity and h base member.

3 Claims, 7 Drawing Figures PATENTEB MAY 23 1972 SHEET 1 [IF 2 INVENTOR. rQ/cHn/w C. DEM/066V BY f PATENTEDMAY23 I972 3, 665,478

I NVENTOR. Hem/e0 C. DEM/056V HTTORA/ Y 1 FOLDABLE ANTENNA OPERABLE IN DUAL MODES The invention relates in general to foldable antennas and more particularly, to a rugged antenna for field use which may be transported in a compact size.

BACKGROUND OF THE INVENTION The use of dual mode antennas which are sensitive to a vertical polarized signal at a first frequency and a circularly polarized signal at a second frequency are well known. Moreover, collapsible antennas sensitive to such multiple frequencies and polarizations have been built. For example, there is depicted in U.S. Pat. application No. 755,563, filed Aug. 27, 1968, now US. Pat. No. 3,579,244, a collapsible antenna utilizing a plurality of radiating elements fabricated of flexible thin steel, secured to a telescoping mast in a manner which allows them to be easily retracted for stowing purposes. When the antenna is operationally deployed, the radiating elements, as well as the ground plane elements, are positioned as desired. Such an antenna, while satisfactory for use where extremely light weight antennas are desired, are not satisfactory for use where it is necessary to operate for prolonged periods of time under severe environmental conditions. Moreover, such an antenna cannot be accurately operated'in numerous instances where greater accuracy is desired.

In order to overcome the attendant disadvantages of prior art collapsible multi-mode antennas, the antenna of the present invention is designed to operate under severe environmental conditions. The extending arrns of the antenna are made of a rigid material. Further, unpacking or assembling of the antenna on site is not only simple and rapid, but foolproof, as well.

The advantages of this invention, both as to its construction and mode of operation, will be readily appreciated as the same becomes better understood by references to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts a preferred embodiment of the novel foldable antenna in accordance with the invention in a fully assembled state which can be used for transmission or reception of the signals;

FIG. 2 illustrates a partial sectional view of the base mounting portion of the antenna of FIG. 1;

FIG. 3 shows a partial sectional view of a cavity connecting member utilized in the antenna of FIG. 1;

FIG. 4 depicts an exploded perspective view of a monopole radiating element utilized in the antenna of FIG. 1;

FIG. 5 illustrates a sectional view of the cylindrical casing member utilized to mount as well as house the antenna of FIG.

FIG. 6 shows an elevational view of one of the plates in the casing member ofFlG. 5; and

FIG. 7 depicts an exploded perspective view of the base mounting portion of the antenna FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown in FIG. 1 a preferred embodiment of the novel antenna in accordance with the invention. The antenna comprises a first plurality of radiating elements 12a, 12b, 12c and 12d, which are separated by 90 and form typical turnstile arrangement radiating elements for generating and receiving a circularly polarized wave. Each of the elements forms an angle of 45 with respect to the vertical axis of the antenna with the ends of each of the elements extending downwardly. A plurality of horizontally extending elements 14a, 14b, 14c and 144 form the ground plane for the elements 12 (a-d). The elements 12(a-d) and 14 (a-a') are fonned of a rigid material, such as aluminum tubing.

A conventional monopole antenna is formed of a vertically extending radiating element 16 with horizontally extending members 18a, 18b, 18c and 18d, forming the ground plane for the vertical monopole antenna 16. A vertical mounting mast 22 interconnects a base mounting member 24 to which the ground plane elements 14 (a-d) are connected and a cavity connecting member 26, to which the radiating elements 12 (a-d), as well as the monopole antenna 16 and the ground plane elements 18 (a-d) are connected. The elements 16 (ad) and the mounting mast 22 may be made of aluminum tubing as well.

The base mounting member 24, which is shown in greater detail in FIG. 2, comprises a flat bottom base plate 32, which is utilized for setting the antenna on the ground or attaching the antenna to a mounting member. Extending from the top of the base plate 32 is a cylindrical structural member 34 having four receptacle plugs 36 spaced along its outer periphery at intervals. Each of the plugs 36 is internally threaded, so as to enable the ground plane elements 14 (a-d) to be readily secured hereto, as well as being rapidly disassembled therefrom, as depicted in FIG. 7. The vertical mounting mast 22 is permanently secured to the top portion of the member 34 and is normally hollow so as to form a conduit for wiring.

The top end of the mast 22 is threadably secured to the cavity connecting member 26, as shown in FIG. 3, and has in its interior, space for housing coaxial cable matching means which are coupled to the radiating elements 12 (ad), as well as the monopole radiating element 16. The cavity connecting member 26 is formed of a cylindrical bottom section 42, and a trapezoidally shaped top section 44, whose larger base 46 is slightly smaller than the top of the cylindrical portion 42 and which tapers to a top surface 48. The monopole antenna 16 is removably threaded to the cavity 26 through the top surface 48 of the trapezoid member 44 and electrical connections to electrical circuitry may be made thereto.

Referring now to FIG. 4, the monopole antenna 16 is normally formed of a thin cylinder and contains at the top end thereof an insulator plug 52, having a central portion 54 whose outer diameter is equal to the outer diameter of the tubing of antenna 16. Further, the plug contains a reduced diameter bottom portion 56 and a top portion 58. The portion 56 fits within the tubing 16 and allows the plug 52 to be secured to antenna 16. Also, mounted on top of the insulator plug 52 is a colinear parasitic element 60 which is approximately twice the length of the monopole antenna for the embodiment as shown, although difierent lengths are possible, depending upon the radiating and receiving characteristics of the monopole antenna, as desired. The parasitic element 60 provides additional gain in the elevation plane for the antenna system. The portion 58 fits within the element 60, allowing mounting thereto.

The ground plane members 18 (a-d) are mounted in a horizontal plane and threadably secured to the bottom section 42 of the cavity 26 at 90 intervals in a manner similar to the elements 14 being secured to the member 24. Moreover, the radiating elements 12 (a-d) are threadably secured to the section 42 and are normally spaced at 90 intervals around the member 26 and interspaced between the ground plane elements 18. The cavity member 26 normally contains transformer and hybrid sections (not shown) for coupling signals to the elements 12 (a-d) in 90 phase delays, so as to generate or receive the desired sense of circularly polarized wave.

A cylindrical casing member 62 terminates at one end at the bottom surface of the base plate 32 and, as shown in FIGS. 5 and 6, has an L-shaped cylindrical flange 64 secured to its end surface adjacent the plate 32. A nut 66 and bolt 68 are utilized to secure the flange 64 to the base plate 32. The bottom of the casing member 62 contains a triangular shaped piercing section 68 which is utilized to insert the casing into the ground, so as to facilitate mounting of the antenna.

Further, positioned within the casing 62, are a pair of plates 72 and 73. The plates have a large central opening 74, an intermediate size opening 76, eight small openings 77, and four still smaller openings 78 extending therethrough. The base plate 32, together with the mast 22, can be removed from the top of the casing. Then each of the members 12 (a-d), l4

(a-d) and 18 (a-d), can be stored in the casing with the members l2 (ad) extending through the openings 78 and the members -(ad) and 18 (a-d) extending through the openings 77 in plates 72, and threadably secured to plate 73. Further, the mast 16, together with element 52 and 54, can be removed and stored in the opening 76. Finally, the cavity member 26 can be unthreaded from the top of the mast 22 and the base plate 32 inverted and the mast 22 inserted through the opening 74 until the top of the base plate 32 abuts the flange 64. Then the nut and bolt arrangement 66 and 68, can be utilized to secure the base plate 32 to the casing 62 in an inverted fashion than that shown in FIG. 1. Moreover, the cavity 26 can be stored on the bottom of the casing 62.

It should be understood that while the antenna has been shown as being operational in two modes, such as a monopole mode and a circularly polarized mode, it should be understood, of course, that other arrangements are possible, for example, the antenna could be used in two different circularly polarized modes as well as different frequencies.

What is claimed is:

l. A foldable antenna for mounting on a base member comprising:

a vertical mounting mast having said base member at one end thereof and a cavity member at the other end thereof;

a plurality of rigid radiating elements depending from said cavity member and being threadably secured thereto; and

a plurality of rigid ground plane members extending from said base member in a plane perpendicular to said mounting mast and being threadably secured thereto;

said cavity having a monopole radiating element threadably secured thereto in a plane parallel to the plane of said mounting mast and a second set of ground plane elements operatively associated with said monopole radiating element threadably secured to said cavity in a plane perpendicular to said mast.

2. A foldable antenna in accordance with claim 1 wherein said radiating elements are designed to transmit and receive circularly polarized waves.

3. A foldable antenna in accordance with claim 1 wherein said radiating elements and said ground plane elements may be removed and transported in a carrying case member which encompasses said mounting mast between said cavity and said base member.

* I! IF 

1. A foldable antenna for mounting on a base member comprising: a vertical mounting mast having said base member at one end thereof and a cavity member at the other end thereof; a plurality of rigid radiating elements depending from said cavity member and being threadably secured thereto; and a plurality of rigid ground plane members extending from said base member in a plane perpendicular to said mounting mast and being threadably secured thereto; said cavity having a monopole radiating element threadably secured thereto in a plane parallel to the plane of said mounting mast and a second set of ground plane elements operatively associated with said monopole radiating element threadably secured to said cavitY in a plane perpendicular to said mast.
 2. A foldable antenna in accordance with claim 1 wherein said radiating elements are designed to transmit and receive circularly polarized waves.
 3. A foldable antenna in accordance with claim 1 wherein said radiating elements and said ground plane elements may be removed and transported in a carrying case member which encompasses said mounting mast between said cavity and said base member. 